A DE image sensor consists of a high-energy (HE) imaging array that is preferentially sensitive to HE x-ray spectrum and a low-energy (LE) imaging array that is preferentially sensitive to LE x-ray spectrum. DE image sensors discriminate between different materials by operating on the principal that different materials have different x-ray absorption spectra. The x-ray absorption spectrum of a specimen's material is a function of the material's elemental composition and its density. Therefore, the ratios of the average absorption coefficients across a sensor's HE array spectral response and the average absorption coefficients across a sensor's LE array spectral response differ between materials. This difference in the absorption coefficient ratios enables the DE image sensor to discriminate between different materials.
Sensors using metal-oxide-semiconductor (MOS), Complementary MOS and Charge-coupled devices (CCD) are sensitive to and susceptible to radiation damage and are generally not practical for DE x-ray imaging applications. When two-dimensional (2-D) arrays are utilized, to avoid radiation damage, the imaging arrays are usually covered with scintillators and fiber optics, which in turn reduce their sensitivity or compactness. Other approaches have been used, but some tradeoff in performance is generally the result.
As is apparent, there has been a long-standing need in the x-ray sensor community for an elegant solution that provides simplicity in design, high sensitivity and accuracy. In view of the prior art's deficiencies, various systems and methods are elucidated below which address one or more of needs of the field.